Science Assessment ~ Topics ~ Control of Variables ~ Misconception CVM023

If two variables change at the same time, one can learn about the effect of at least one of the variables on the outcome (AAAS Project 2061, n.d.).

Items that test for misconception CVM023 in this project (Original Project) and key idea (If more than one variable changes a…)
Item ID Number	Item Description	How Often the Misconception was Chosen
CV022002	In an experiment involving skateboards, in which the size of the wheels and the material the skateboards are made of are both varied at the same time, it is not possible to find out if either of these variables affects the performance of the skateboard.	29%
CV010003	In an experiment involving balls and ramps, if both the height of the ramp and the size of the ball are changed at the same time, no conclusion can be reached about the effect of either of the individual variables on how far the ball can roll.	26%
CV021003	In an experiment on the effect of temperature and soil type on the growth of corn plants, with both variables changing at the same time, no conclusion can be reached regarding the effect of either temperature or soil type on the growth of the plants.	25%
CV020003	In an experiment on the effect of temperature and the amount of water on the growth of plants, with both variables changing at the same time, no conclusion can be reached regarding the effect of either amount of water or termperature on the growth of the plants.	25%